Automatic flap control for airplanes



April 13, 1943. GAST 2,316,235

AUTOMATIC FLAP CONTROLS FORAIRPLANES' Filed Oct. 23. 1940 Inventor:

Patented Apr. 13, 1943 UNI STATE aurorm'rlcrmr coN'rRon Fon a 7AIRPLANES n.

I l'slrlch Gastybessamvestedi'n the-Alien 1 1 l ropertycustodian v Yhpplicationoctober 22, 1940;, Serial No.. 1ss2,425 r i v InGermanyJuly10,1939, (Cl. 244-78)"- v v II CIaim s. This inventionrelates toautomatic flap controls for airplanes. The use of flaps and thelikefii'orjincreasing the lifting power of airplanes isconstantly@increasing, and experience has i shown the need of means for,automatically returning these flaps to or towardstheir inoperativepositions when the-air pressure; exerted the "flap; and to inount thecylinder for'm'ovement so" that through this movement the ilap;

inclination may bevarled I v t g A further object, of the invention isto provide such'amautomatic flap control whereinjthe' cylinder issupported by a lever one extremity of "against them exceedsapredeterminedmaximum and threatens to become dangerous. Y QITo' this endarrangements have which have not proved entirely satisfactory; Forinstance hydraulic means have been employed to their inoperativepositions when the air: presbe'endevised having relief valves set toopen at certain pres:

1 sures and therebypermit the retumof the flaps w sure acting againstthem becomes excessive. Due, however, bothfto' the friction to beovercome in the mechanism itself and the wind resistarice against whichthe flaps have to be moved to theiroperativepositions it isoftenfound-impossible to use such an arrangement because the "pressurerequired to overcome both the friction and the air resistance to movethe fiapsoutwardlyn V {is greater than thatrequiredmerely toretain {theflaps in operative position even when they are subjected to suchexcessive air pressure'as to threaten their destruction. The next stepthen thevalve setting was a tedious lob involving a number of. testflights, and often then only rtesulted in a more or lessapproximately-correct setting. 11 v 1 It isan object of this inventionto provide an; i V automatic flap control by which the above nameddrawbacks are overcome and wherein more sen-e fsitiver'neans areprovided for moving the flapto L fits operative position and retainingit in that r position unless and untilthe air pressure actin f againstit exceeds a predetermined: limit, and t when that limit isexceededmovingthe flap to or towards its inoperative position until therair loadacting againstit dropsbelow the aforesaid fl jlimitmhereupon the flap isagain moved to its operative position. I ":Another object of theinvention is to provide an automatic nap control including auhydrauliccylinder having a piston therein adaptedtomove which moves betweenstopsagainst one of which the lever is normally held: and wherein amechg afnism operated by movementof the lever releases thepressure-inthehydraulic-feed line to the cylinder. n' Q Yeta'nother object of theinvention is to pro'- vide such an automatic flap control wherein meansareprov'ided for preventing fluttering of the ,flap during cylinder;

movement of the lever and Another objectof the invention'isto providesuch an 'automatic flap control wherein the hymechanically or i drauliccircuit may be either electrically controlled. V n

Still another object ofthe invention is to providean automatic flapcontrol in one embodi- V ment of which movement of theleve'r from itsnormalposltion breaksan electric circuit and cuts oif the hydraulic nowto the 'cylinder'where v by thelflap-ismoved to and retained initsoperative position, and wherein upon completion of the pivotalmovementof the lever a second electric circuit is closed whereby the hydraulicsystem is set to permit movement of the pistonvin the cylinder by whichthe flap is returned to its inoperative position. Y

Having thus briefly of the objects and advantages of. the invention ing,in which: n Figure 1 illustrates a diagrammatic view of the I will-nowdescribe ,two preferred embodiments thereof with the-aidof theaccompanying drawinvention wherein'the hydraulic now is mechanicallycontrolled, and

Figure 2 showsia modification thereof wherein the hydraulic mechanism"is -electrically con "trolledn. r n W x a n r Referring to Figure 1, 1denotesatank con nected by a suction pipe 2 to a pump 3 from whichliquid under pressure is delivered to a rotary valve 5 through adischarge pipelfrom which a return line ill having a relief valve 9therein, extends back tothe tanki toelimit the pressure of the liquiddischarged thelp urnp.

The rotary valve I has fourconnection's; one

connected to the discharge pipe 4, one to 'a return connection I Iextending back to the tank I,

- one to a flap operatingline l2, and onev'to'a flap return line It;provided in this valve is a rotary and Y broadly statedsome t plug ahaving three separate passages 6, I and than the valve 32.

8 formed therethrough.- By the passage 6 the discharge pipe 4 is shownconnected to the retum connection II, and the passages I and 8 are theninoperative. However by turning the plug 5a, the discharge pipe 4 may'be connected through the passage 8 to the flap operating line I2 atwhich .time theflap return line I6 is connectedby the passage. 1 to thereturn connection I I, orthe discharge pipe 4 may be connected to thefiap return line I6 through the passage I at which time the flapoperating line I2 is connected through the passage 8 with the returnconnection II. When the rotary plug 5a is in either of these latterpositions the passage 6 is inoperative,

end I3 of the cylinder ing movement of the lever 22 towards the stopvPivoted on a pin 2 I, supported from a fixed portion of an airplane, isa lever 22 mounted for movement on one extremity of which is a cylinderI I 4 having a piston I'I therein from which a rod I8 extends. Pivotedon a pin I9 supported by another fixed portion of theairplane is a flap20.

to which the outer extremity of the rod I8 is soconnected that movementof the piston IT, or of the cylinder I4 when the piston remains stationary therein,.causes movement of the flap 20 about the pin I9. Theflap operating line I2 and the flapreturn line I6 are connected toopposlte'ends I3 and I5'of th said cylinder respectively, and, since thecylinder is intended to ,move somewhat when the lever 22 swings aboutits axis, the lines I2 and I6 are'made sufficiently flexible to permitsuch movement.

q The extremity of the lever 22 remotefrorn the cylinder I4 extendsbetween two stops 24 and 25 mounted on fixed portions of the airplane,and

. which limit the swinging of the lever 22 in both directions. 'Mountedalso one fixed portion of the plane and in threaded engagement therewithis an adjusting screw 23' having one extremity of a coil spring23seeured thereto and its oppositeextremity secured to the free end ofthe lever 22. This spring tends to retain th lever 22 against ,thestop24 and the cylinder I4 in itspositionshown; by adjusting the screw 23'the ten- "sion of the spring. may be varied. Thus maximum air pressureto be'withstood by the flap 20 when turned to its operative position,before movement of the lever 22 about the pivot pin 2I and thereforemovement of the cylinder I4 occurs,

maybe varied. Extending from the flap operating line I2 is a branch I2aterminating in a valve chamber 28 having a piston valve 2I.therein..Arod 26 extends between and is connected at opposite 'ex tremities tothe lever 22 and to the valve 21. Ex

tending also from the valve chamber 28 is a relief line I la from whicha circulating pipe 33extends having a relief valve 32 therein andconnected at its opposite extremity. to the flap return line I6; therelief line lId is also preferably connected to the return connection IIthrough a pressure retaining valve 3I set to open at a higher pressureThe opDOsite ends of the valve chamber 28 are connected by a by-passpipe 29 having a suitable valve 30 therein to retard the flow of liquidin either direction through the said pipe and prevent rapidreciprocation of'the piston valve 2I1and consequent fluttering of theflap 20 sure exerted against theflap 20.

- connection I I.

stop '24, and if during this movement excessive.

air pressure continues to be exerted against the flap the levercontinues to swing until it strikes the stop 25. During the first partof the swing- 25 the piston I1 is held stationary in the cylinder I4 byhydraulic pressure from the flap operating line I2, but when the leverhas moved suiiiciently to cause such movement of the piston valve 21that the branch I2a is connected with the relief line I Ia through thevalve chamber 28 then liquid under pressure flows from the flapoperating line I2 through the circulating pipe 33 and the relief valve32 to the .flap return line I6 and thus to thecylinder end I5. Then theflap 20 is swung back'towards its inoperative position by movement ofthe piston I! pushed inward by air pres- However as soon as the airpressure acting against the flap drops below that for which the spring23 isset, that spring moves the lever 22 back towards the stop 24thereby moving the piston valve 21 to sever the connection between uponpressure is again built up in the cylinder end I3 and at the same timethe cylinder I4 is moved forward towards its normal position.

If it is desired to render the flap 2!] inoperative for normal flightthe valve 5 is so set that the discharge pipe 4 isconnec ted to the flapreturn line 7 I6, and the flap operatin line I2 to the return cylinderend I5 which retains the piston I'I atiits rear position in the cylinderI4. a

In the modification shown in Figure 2 the same ,mechanism iselectrically instead of mechanically v operated. The tank I, suctionpipe 2, pum 3,1

discharge pipe 4, and return line III with its relief valve 9 are againemployed. The discharge pipe 4 is connected to a ,valve 34 to which areturn connection II and an actuating pipe 46 are also connected.- Inthe valve 34 is a plunger 31 which is normally retained in its positionshown by a spring 40 so that the discharge pipe 4 is connectedtotheretllrn connection II; Howeveriby energizing the solenoid 43through an electric circuit hereinafter described the plunger 31 ismoved to close the return connection 'II and affordrcommunicationbetween the discharge pipe 4 and the actuating pipe 46.. Thelatterterminates in a valve 35 having a plunger 38 therein .,-nonnal1yretained in its position shown by a spring 4I so that the actuating pipe46 is normally connected to a flap operating line I2b which terminatesin the end I3 of the cylinder I4. Ex-

ating line 45 upon movement of the plunger 33 tending from-the valve 35is alsoa flap return line Ifib which terminates in the end I5 of thesaid-cylinder and which is connected to the actu by the solenoid 44,whereupon connection between the actuating pipe 46 and theflap'operating line I2b is interrupted. 7

Extending from the returnconnection II is a relief line IIb havingapressure retaining valve 3Ia therein and terminating at its oppositeextremity in a valve 36, between which and the said' valve 3 la acirculating pipe 33a is provided which connects the relief line I Ibwith the actuating I4 and the flap 2D is turned The pressure is exertedin the pipe .46 and has a relief valve 32a therein. A

. plunger 39 in the valve 38 is normally soheld by a spring 42 that therelief line i lb is' connected tofabranch l6, of theiiap return linelib, but

, when the plunger- 39 is moved by a solenoid'45 it connects the relief,line ljlb with a branch l2 of the flap operating line l 2b.

The arrangement r the cylinder 14 with its piston l1 and rod l8connected to the fiap2ll pivoted on a pinl 9 is the same as before,andthecylswitch is closed, are connected to a lead 64. Ob-

inder is again secured to the pivoted lever 22 the I free extremity of.whichlswings between the two stops 24 and and is normally retainedagainst of the lever 22 in contact with the latter adjacent its freeextremity, and the lever is so constructed as to constitute insulationbetween the contacts 41 and 48. When the lever is in the position shownthe contact 41 is in electrical engagement the stop 24 by a spring 23the tension of which is i adjustable through the adjusting screw 23".Spring contacts 41 and 48 remain at all positions with the stop 24 whichalso functions as an elec- .trical terminal, and then the contact 48isdisengaged from the stop125 which functions, also as ,a terminal.

, From a source of power 60 a lead 6| extends to the solenoid I43, andfromthe latter another wire 62 runs which is connected to the springcontact 41; ,When theflever 22 is in the position shown thiscontact 41is. inelectrical engagement with the stop 24 from whicha wire 63 extendsto one side of a switch 49, theopposlte side of which is [connectedthrough a lead 64 to the source of power 60. 'Ihus when the switch 49 isclosed the solenoid, 43, is operativewhenever the lever 22 is in itsposition shown. At that time a hydraulic flow occurs from the dischargepipe 4 through i the actuating pipe 45, valve and flap operating =line;l2b to the cylinder 'end ,l3, thereby moving thepiston l1 and rod l8forward and turning the i flap 20 to its operative position. Then liquiddisplaced from thecylinder end If; flows through the flap return linelBb and branch l6 through the valve 36, the relief line llb, valve 3laand returnline ll back to the tank I.

When the lever 22 swings away from the stop 24' the circuit through thespring contact 41 and solenoid 43 is broken, and the spring returns theplunger 31 inthe valve 34 to its position shownand closes the connectionbetween the viously when the switch is closed'all three solenoidsareienergized Then a hydraulic flow oc curs from the discharge pipe 4,through the valve 34, actuating pipe 45, valve 35 and flap return linelib, at which time the flap operatingline the said alterations andmodifications fall within the scope of the appendedclaims.

What I- claim is:

comprising a pivoted lever, a cylinder mounted for substantially axialmovement on one extremity of the lever, means tending to retain thelever at one end of its travel. and the .cylinderin its normal position,a piston in the cylinder, means for introducing a pressure medium'intothe cylinder for moving the piston, a movable flap adapted to be movedfrom an inoperativeto an operative position to afford resistance to anair stream, a rod connected to the, piston and to the flap for movingthe latter, and, said. flap being adapted to be moved fromitsioperativetowards its inoperative position by excessive air pressure therebymoving the cylinder andlever while the piston is held stationary in thecylinder ,by the pressure medium.

'2. An arrangement comprising the combination set forth in claim 1,wherein the means tendingto hold the cylinder at one limit of its travelconsists of a spring which returns the cylinder to its normal positionand thereby returns the hen to its operative position when the airpressure acting against the latter drops below a predetermined amount.

discharge pipe 4 and the actuating pipe 46, and

opens the former to the return connection ll.

Due to the provision of the relief valve 3la in the relief line llb allthe liquid then flows back to the tank I. When the lever 22 moves thespring contact 48 into electrical engagement with the stop 25 a circuitis closed through a wire 6| extending from the lead 8| to the solenoids44 and 45, from the latter through a wire connected. to the stop 25 andfrom the contact 48 through a wire 64' connected to the wire 64.- Thenthe plungers 38 and 39 are so moved that the following: flow results asthe piston I1 is moved to the left (Figure 2) by air pressure actingagainstthe flap 20: From the cylinder end ill to the end l5 through theflap operating line l2b and branch l2, valve 36, relief line lib,circulating pipe 33a and valve 32a, actuating line 48, valve 35 and flapreturn line lBb.

i A third electric circuit is provided for directing the hydraulic flowso that the flap 20 is positively maintained in its inoperative positionshown.

- This consists of a double switch 50 having connections 65' and 82'connected to the wires 65 l and 52 respectively, both of which, when the3. An arrangement comprising the combination set forth in claim 1,wherein the means tending to'hold the cylinder atone limit of its travelconsists of a spring, and means for adjusting the tension of the latterwhereby the air pressure required to move the flap towards itsinoperative position and the cylinder substantially axially may bevaried.

4. An arrangement of the character described comprising a pivoted flapadapted to be moved from an inoperative to an operative position tooffer resistance to an air stream, a cylinder mounted for limitedmovement substantially in the cylinder, a rod extending from the pistonand 1. An arrangement of the character described connected to the flapto impart pivotal movement adapted to be moved from an inoperative to anoperative position to offer resistance to an air stream, a cylindermounted on the airplane for movement substantially in alignment with itsaxis, stops limiting the cylinder movement, a

means tending to retain the cylinder at one limit of its travel,a'piston in the cylinder having a rod extending therefrom connected tothe flap position, said flap'being adapted to be moved to-v wards itsinoperative position byjexcessive air pressure exerted against it andthereby move the.

cylinder towards its outer limit of travel while the piston is heldimmovable in said cylinder by hydraulic pressure, and valve meansoperated by movement of 'thecylinder for permitting equalization ofthe'hydraulic flow from one end of the cylinder to the other when saidcylinder has been moved adjacent its other limit of travel.

6. An arrangement of the character described comprising a pivoted lever,a spring tending to retain itinnormal position, a cylinder connected tothe lever for'movement therewith, a piston in the cylinder, a pivotedflap, a rod extending from the piston and connected to the flap to-movethe latter, jmeans for admitting hydraulic pressure into one end 1 ofthe cylinder, said flap being adapted to be turned to its operativeposition by the pistonand towards its inoperative position by excessiveair pressure acting against it thereby 'moving the cylinder and lever,valvemeans operated by movement of the lever, piping connected to thevalve means and cylinder through which a hydraulic'flow'occurs from oneend of the cylinder to the-other when said valve means is opened topermit movement of the piston in the cylinder,

cylinder to their normal positions when the air pressure acting upon theflap drops below a predetermined pressure and means permitting theescape of hydraulic pressure from the other end operated valve meanswhereby hydraulic pressure -30 said spring being adapted .to return thelever and I,

may also be exerted in the other end of the cylinder to positivelyretain the flap in its inoperative position. 7

9. Anarrangementof the: character described comprising a cylindermounted for substantially axial movement, a piston therein, meansincluding valves for admitting a pressure medium into either end of thecylinder, mechanical means for selectively operating the valves, apivoted flap adapted to be moved either position or to an operativeposition to ofier resistancetoan air stream, a rod connected to thepiston and to the flap to move the'latter, said flap being'adapted to bemoved from its operative towards its inoperative position by excessiveair pressure acting thereagainst thereby moving the cylinder when thepiston therein is held immovable in said cylinder by the pressuremedium, and means tending to return the cylinder to its initialposition.

'10. An arrangement of the character described comprising axialmovement, a piston therein, means including valves for admitting apressure mediuminto either end of the cylinder, electrically operatedmeans for selectively operating the valves, a pivoted flap adapted to bemoved either to an inoperative position or to an operative position tooffer resistance to an air stream, a rod connected to the piston and tothe flap to move the latter, said flap being adapted to be moved fromits operative towards its inoperative position by excessive air pressureacting thereagainst thereby moving the cylinder when the piston thereinis held immovable in said cylinder by the pressure medium, and meanstending to return the cylinder to its initial position.

11. An arrangement of the character described comprising the combinationset forth in claim 10, including a lever on which said cylinder ismounted, and the electrically operated means being operated throughmovement of said lever.

ERICH GAST.

to an inoperative 9, cylinder mounted for substantially

